A semiconductor module provided with a plurality of switching elements, and a plurality of control circuits which respectively drive the switching elements on and off, is used as a constituent component of an inverter device for driving a load, such as a motor. FIG. 4 is a diagram showing the principal schematic configuration of a semiconductor module IPM which is used in an inverter device that drives a tri-phase motor M; wherein Q1, Q2 to Q6 are six switching elements which respectively form three half-bridge circuits.
Furthermore, D1, D2 to D6 are freewheeling diodes which are respectively connected inversely in parallel to the switching elements Q1, Q2 to Q6.
Here, in the three half-bridge circuits, the switching elements Q1, Q2, Q3, which are connected commonly to a power source terminal P to which a DC voltage is applied, and which form an upper arm, and the switching elements Q4, Q5, Q6, which form a lower arm, are configured so as to be connected directly to each other. In these half-bridge circuits, the connection points between the switching elements Q1 (Q2, Q3) which form the upper arm and the switching elements Q4 (Q5, Q6) which form the lower arm become output terminals L1 (L2, L3) which supply power to the U (V, W) phases of the tri-phase motor M.
Furthermore, the other ends of the switching elements Q4, Q5, Q6 which form the lower arm are respectively connected to ground-side terminals N1, N2, N3. These ground-side terminals N1, N2, N3 are grounded via shunt resistors R1, R2, R3, for example. The switching elements Q1, Q2 to Q6 are power semiconductor elements constituted by IGBTs or MOS-FETs provided with a gate, which is a control electrode. A semiconductor module IPM having a configuration of this kind is introduced in detail in Japanese Patent No. 3394377, for example.
The control circuits IC1 to IC6 which are provided in the semiconductor module IPM and which respectively drive the switching elements Q1, Q2 to Q6 on and off are provided with output amplifiers A1 to A6 as drive circuits which apply a drive signal to the gate of the switching elements Q1, Q2 to Q6, as shown in FIG. 5, for example. Furthermore, the control circuits IC1 to IC6 are respectively provided with abnormality detection circuits ED1 to ED6 which detect abnormalities such as overcurrent or overheating in the switching elements Q1, Q2 to Q6, by monitoring the current which flows to the switching elements Q1, Q2 to Q6, and/or the operating temperature, and the like.
The semiconductor module IPM is configured so as to prohibit the operation of the output amplifiers A1 to A6 via the output control circuits C1 to C6, thereby protecting the switching elements Q1, Q2 to Q6, when an abnormality is detected by the abnormality detection circuits ED1 to ED6. Furthermore, simultaneously, the semiconductor module IPM is configured so as to externally output, via the switching elements S1 to S6, for example, abnormality information about overcurrent and/or overheating, etc. that has been detected by the abnormality detection circuits ED1 to ED6, as operating status information for the control circuits IC1 to IC6.